Signal tracing system and method

ABSTRACT

A system and a method are for determining the origin of a signal received by a pay television subscriber in a given region. A system includes an encryption device located at a main operator, a transmission device adapted to transmit an encrypted video signal towards at least one local operator, and a decryption device at the local operator. The decryption device includes an identification device for replacing all or part of the decrypted video signal with an identification signal characterising the decryption device.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/IB02/00555 which has an Internationalfiling date of Feb. 25, 2002, which designated the United States ofAmerica and which claims priority on Swiss Patent Application number CH0345/01 filed Feb. 26, 2001, the entire contents of which are herebyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention is generally of the field of information signaldistribution by several intervening parties. More particularly, it isdirected to determining, in an indisputable manner, the origin of thesignal.

BACKGROUND OF THE INVENTION

In the case of a pay television broadcasting, several interveningparties cooperate so that the subscribers can receive the desiredemissions.

Amongst these intervening parties we find firstly the main or nationaloperators who offer the important television channels. It should beknown that a same channel can be offered by more than one nationaloperator. These national operators can either be the creators of thischannel or they can sign broadcasting contracts with other local orforeign broadcasters. These national operators thus offer a servicepalette to local operators, the latter being connected to a certainnumber of subscribers.

A local operator can be active in several regions and the contractsbinding this operator to a national operator are generally based on thenumber of subscribers to which the channel will be broadcasted oraccording to a geographical definition. Thus it is possible for a localoperator to sign a broadcasting contract for a region A although thisoperator broadcasts also in regions B and C. Then it exists technicallya possibility for this operator to also broadcast in the regions B and Cwithout the national operator being able to intervene.

This is particularly the case in the case that the illegally broadcastedchannel in the region B is also offered by another national operatorthrough another local broadcaster. It is then difficult for the mainoperator to know if the signal received in the region B comes from acontract signed only for the region A or if it comes from anothernational operator. In fact, each subscriber can be connected to morethan one local operator, the latter being supplied by many nationaloperators.

It is well known that the national operators transmit their signals tothe local operators in encrypted form. For the decryption operation,decryption devices are supplied by the national operator. These devicescan include a decryption module and a smart card, the latter being incharge of ensuring the access control. Once the signal is decrypted bythe decryption device, the local operator can dispose of it as it likes.It is then allowed for the local operator to compose its televisionbouquet with a selection of channels subscribed from several nationaloperators.

SUMMARY OF THE INVENTION

An aim of an embodiment of the present invention is to propose a systemand a method for determining the origin of the signal received by asubscriber in a given region.

An objective my be achieved by a system comprising encryption meanslocated at a main operator, transmission means of an encrypted videosignal towards at least one local operator, and decryption means at thelocal operator, wherein the decryption means comprise identificationmeans replacing all or part of the decrypted video signal with anidentification signal characterising the decryption means.

An identification signal includes a visual signature added to any regionof the screen. It can have the form of a text field at the bottom of thescreen, a background overlaying the real image, etc. When this signal isadded to the video signal, all the subscribers to whom the channel isbroadcasted will see an identification message appear on their screens.

In order to be able to trace the origin of the data transmitted to asubscriber this message will contain an identifier specific to thedecryption device responsible for the decryption of the main operator'ssignal. The latter may thus prove that the channel available for anygiven subscriber is the result of its transmission towards a given localoperator.

According to our previous example, a subscriber of the region B servesas a test to determine if the contract with the local operator has beenrespected. If the identification message appears on his/her screen thelocal operator has not respected its contract that was limited to theregion A.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be better understood with the help ofthe following detailed description which refers to the annexed figurewhich is given as a non-limiting example.

The single figure represents a system of pay television broadcastingwith several intervening parties.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

On the left of the figure are two main operators OPP1 and OPP2. Theseoperators propose their broadcasting channels to all the local operatorsrepresented by OPL1 and OPL2.

The link between the main operators and the local ones is done byexample by satellite or by cable. Many local operators can receive thesesignals and due to this it is necessary to encrypt the data in order tocontrol the use.

To this effect a decryption module MS is placed at the local operatorand is in charge of decrypting the signal encrypted by the mainoperator. This module has the form of a pay television decoder and islinked to a security module that has the form of a smart card. This cardcontains the keys that are necessary for the functioning of thecryptographic processor contained in the decryption module.

In this way, each main operator that sings an agreement with a localoperator also installs such a decryption module MS in the premises ofthe local operator. The signal coming out of the decryption module MS isin plaintext and no other control at that stage can be carried out bythe main operator.

The local operator composes its offer, which is an assembly of severalchannels acquired from several main operators (OPP1, OPP2), and encryptsit according to a protocol and means that are specific to it. This newsignal is then broadcasted by different ways, for example by cable or byradio-relay network, to the target regions (RA, RB, RC) of thisoperator. At the subscriber's end there is the final decoder (STB) incharge of decrypting the signal of the local operator.

According to our example of FIG. 1, the region B (RB) is supplied by twolocal operators either the operator OPL1 and OPL2.

The main operator OPP1 signs a broadcasting agreement of channel S withthe operator OPL1 for the region A (RA). It should be noted that thischannel is equally proposed by the main operator OPP2 that sings anagreement with a local operator OPL2 for the region E (RE).

In the case where the channel S is also broadcasted in the region B, itis difficult for the main operator OPP1 to know if a decoder STBreceives the channel S from the operator OPL1 or from OPL2, the latteralso being able to broadcast in other regions the channel S.Furthermore, it may happen that the decoders STBy and STBx are in factthe same decoder, the latter having the subscription rights from bothlocal operators.

This configuration is even more complicated by the fact that the localoperator OPL2 can sign a broadcasting agreement for the region B eitherwith the operator OPP1 or with the operator OPP2. The simple fact ofadding a logo on the signal broadcasted by a main operator does notallow to determine if the agreements for each region are beingrespected. This is why, according to an embodiment of the invention, themain operator OPL1 sends a command to the decryption module MS1 so thata signal identifying this module is added to the screen of the decodersthat receive the signal issued from this decryption module MS1.

This identification generally includes the identification number of thedecryption module and the number of the security module (smart card). Inthis way these numbers prove indisputably the origin of the channel Sfrom a decoder for a given region. This identification lasts severalseconds in order not to disturb the subscriber.

This duration can be managed either by the decryption module itself orby a command sent by the main operator to deactivate this function.

According to a first embodiment, this signal replaces the bottom part ofthe image with these indications of alphanumeric type.

The region modified by this information can be randomly chosen toprevent the local operator from detecting the identification mode andfrom replacing the corresponding part with an advertisement text.

According to a second embodiment, the identification data are added inthe background on the image. It is then impossible for the localoperator to hide this information.

According to one embodiment the command sent by a main operator iscalled global, that is that it makes react all the decryption modules(MS1, MS1′). According to another embodiment the command sent by a mainoperator is called selective, that is that it makes react only thedecryption module that is called.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. System for identifying an origin of a signal broadcasted to asubscriber, comprising: an encryption device located at a main operator;a transmission device, adapted to transmit an encrypted video signaltowards at least one local operator; and a decryption device located atthe at least one local operator, adapted to provide the local operatorwith a decrypted signal for broadcasting to subscribers, wherein thedecryption device includes a substitution device, adapted to replace atleast part of the decrypted video signal with an identification signalcharacterising the decryption device.
 2. System for identifying theorigin of signal according to claim 1, wherein the decryption deviceincludes a decryption module and a security module.
 3. System foridentifying the origin of a signal according to claim 2, wherein theidentification signal includes an identifier of the decryption moduleand an identifier of the security module.
 4. System for identifying theorigin of a signal according to claim 1, wherein the identificationsignal is placed in a randomly defined area on a screen.
 5. System foridentifying the origin of a signal according to claim 1, wherein theidentification signal is overlaying a current image such as abackground.
 6. Method for identifying the origin of a signal broadcastedto a subscriber, the method comprising: encrypting a video signal by amain operator; transmitting the encrypted signal to several localoperators; decrypting the encrypted signal by a decryption module of anenabled local operator and disposing of the decrypted signal; and,broadcasting of the decrypted signal to subscribers of said localoperator, wherein: at least part of the decrypted signal is substitutedwith an identification signal identifying the decryption module prior tobroadcasting.
 7. Method according to claim 6, wherein the identificationsignal replaces a part of an image formed by the decrypted signal in anyregion of the image.
 8. Method according to claim 6, wherein theidentification signal is overlaying a current image such as abackground.
 9. A method according to claim 6, wherein an identificationcommand by the main operator is to at least one decryption module. 10.System for identifying an origin of a signal broadcasted to asubscriber, comprising: transmission means for transmitting an encryptedvideo signal towards at least one local operator; and decryption means,located at the at least one local operator, for providing the localoperator with a decrypted signal for broadcasting to subscribers,wherein the decryption means includes substitution means for replacingat least part of the decrypted video signal with an identificationsignal characterising the decryption means.
 11. System for identifyingthe origin of a signal according to claim 10, wherein the decryptionmeans includes a decryption module and a security module.
 12. System foridentifying the origin of a signal according to claim 11, wherein theidentification signal includes an identifier of the decryption moduleand an identifier of the security module.
 13. System for identifying theorigin of a signal according to claim 10, wherein the identificationsignal is placed in a randomly defined area on a screen.
 14. System foridentifying the origin of a signal according to claim 10, wherein theidentification signal is overlaying a current image such as abackground.
 15. An apparatus, comprising: a decryption device associatedwith a local operator, adapted to decrypt a previously encrypted videosignal transmitted toward the local operator, to produce a decryptedsignal for broadcasting to subscribers, wherein the decryption deviceincludes a substitution device, adapted to replace at least part of thedecrypted video signal with an identification signal characterising thedecryption device.
 16. An apparatus according to claim 15, wherein thedecryption device includes a decryption module and a security module.17. An apparatus according to claim 16, wherein the identificationsignal includes an identifier of the decryption module and an identifierof the security module.
 18. An apparatus according to claim 15, whereinthe identification signal is placed in a randomly defined area on ascreen.
 19. An apparatus according to claim 1, wherein theidentification signal is overlaying the current image such as abackground.
 20. A method, comprising: decrypting a received previouslyencrypted signal using a decryption module associated with an enabledlocal operator; and broadcasting the decrypted signal to at least onesubscriber of the local operator, wherein at least part of the decryptedsignal is substituted with an identification signal identifying thedecryption module prior to broadcasting.
 21. A method according to claim20, wherein the identification signal replaces a part of the imageformed by the decrypted signal in any region of the image.
 22. A methodaccording to claim 20, wherein the identification signal is overlayingthe current image such as a background.
 23. A method according to claim20, wherein an identification command by a main operator is to at lestone decryption module.